Ephemeris Time

Ephemeris Time was a timekeeping system introduced to provide a more uniform measurement of time based on Earth's orbital motion rather than irregular Earth's rotation. It uses precise astronomical observations, particularly the positions of celestial bodies like the Sun and planets, to define a standard time scale. This approach accounted for variations in Earth's rotation, which affected traditional timekeeping based on the day. Ephemeris Time was essential for astronomy and space science, ensuring consistent and accurate timing for observations. It has since been replaced by atomic time standards, but it was a crucial step toward modern, highly precise time measurement.